1. Field of the Invention
This invention relates generally to an electrode apparatus for use in a continuous glass melting furnace and, more particularly, to an easily replaceable electrode device which extends into an open top portion of a tank type glass melting furnace.
2. Description of the Prior Art
In melting glass making materials in conventional continuous tank type furnaces, considerable difficulty has been encountered in obtaining uniform melting of the materials and utilizing the maximum efficiency of the heat supply because of the normal practice of supplying heat from overhead flames to melt the raw materials and refine the melted materials at elevated temperatures. In this process, raw batch material and scrap glass or cullet are charged into one end of the furnace and molten glass is removed from its other end. The glass, in moving through the furnace, passes successively through melting, fining and cooling areas which are contiguous with one another. Heat is applied over the upper surface of the bath of glass in both the melting and fining areas.
In such a furnace, the charging of relatively cold glass making materials into the charging end of the furnace, creates a problem in producing a homogeneous bath of molten glass since the batch materials are cold. In this process, a blanket of unmelted batch materials lies on top of the molten materials at the charging end of the furnace and, at times, when the quantity of glass being produced is large, the rate of feeding cold batch material into the charging end of the furnace may reach a stage where the molten glass materials therein become unduly cold and may even cause the molten materials to "freeze" or "solidify", particularly along the walls defining the open charging end. This, of course, disrupts the effective circulation of the molten glass below the cold blanket and interferes with the homogenity of the molten glass bath in the furnace.
In order to overcome this problem, auxiliary heating devices, such as heating electrodes have been provided within the charging end of the furnace to supply additional heat and thereby maintain the temperature of the molten bath materials at a level where the effective circulation of molten glass occurs.
Heretofore, heating electrodes have been placed in the side walls or floor of the charging area or doghouse. Conventionally, holes are drilled in the refractory side and rear walls of the doghouses and electrodes having water cooled jackets are inserted through the holes into the bath of molten glass. As the electrodes burn off within the molten glass, new sections are added at the rear end and they are driven through the water cooled jackets. However, the electrodes have a tendency to corrode within the jackets and it thus becomes very difficult to change them. In addition, the water cooled jackets frequently spring leaks, causing serious difficulty including, at times, complete "freezing" of the molten glass bath within the doghouse. This, of course, creates a problem of removing the solidified glass from the charging area of the furnace.
Also, since such heating electrodes are fixedly positioned within the charging end of the furnace, a plurality of electrodes is required to provide flexibility in the temperature distribution therein for overcoming localized cool areas occurring in the doghouse.